Database Reference
In-Depth Information
F IGURE 1.3
A simple customer entity expanded to support three addresses
This method has several problems. We now have three sets of attri-
butes in the same entity that hold the same data. This is bad from a nor-
malization standpoint, and it is also confusing. We can't tell which address
is the customer's home or work address. We also don't know why the cus-
tomer had these addresses on file in the first place. The model, as it exists
in Figure 1.3, is not very scalable, and this is the kind of problem that can
occur when you need to expand the model. An alternative, more scalable
model is shown in Figure 1.4.
F IGURE 1.4
An expanded customer model to include a separate address entity
 
Search WWH ::




Custom Search